When electronic devices are manufactured, various plasma treatments are performed on an object to be processed. In a plasma processing apparatus for performing plasma treatment, a plasma is generated by exciting a gas supplied into a processing chamber. The object to be processed is processed by the plasma thus generated.
In the plasma processing apparatus, the object to be processed is mounted on a mounting table. The mounting table includes a lower electrode and an electrostatic chuck. The electrostatic chuck is provided on the lower electrode. The lower electrode is electrically connected to a high frequency power supply for generating a high frequency power.
In the plasma processing apparatus including such a mounting table, a focus ring may be used to perform uniform plasma treatment on the object to be processed, as described in Japanese Patent Application Publication Nos. 2005-277369 and 2005-303099. The focus ring is made of a dielectric material and disposed to surround the electrostatic chuck and the object to be processed. Further, the focus ring is supported by a dielectric member that is disposed to surround the lower electrode of the mounting table. By providing the focus ring, it is possible to control a sheath potential at an outer side of an edge of the object to be processed. As a result, the in-plane uniformity of the plasma treatment of the object to be processed can be controlled.
Meanwhile, there are various methods for exciting a processing gas. Recently, a plasma processing apparatus for exciting a processing gas by using a microwave attracts attention.
In the plasma processing apparatus using a microwave, the microwave propagates via the focus ring and the dielectric member which are disposed around the mounting table. The microwave propagating in such a manner may affect various components provided below the mounting table. For example, the microwave may make a high frequency power supplied from the high frequency power supply to the lower electrode unstable or cause malfunction of various measurement devices.